The present invention relates to an information input/output apparatus using a projection type liquid crystal electro-optical device. The invention also relates to an information input/output apparatus that can input a position on a display surface which position is indicated by contact to the display surface, light emission, or some other means. Further, the invention relates to an information input/output apparatus that reads image information such as a drawing placed on a display surface, or displays readout image information.
There are conventionally known apparatuses which allow an information signal to be externally inputted with respect to information displayed on the display surface of a display device such as a CRT or a liquid crystal electro-optical device while causing an operator to feel as if he were writing characters on a sheet with a writing tool, and which display an image corresponding to the input information signal on the display surface.
To allow input of an information signal to the display device, the display surface is equipped with a position detecting means for detecting a position on the display surface. When a certain external force such as pressure, magnetic force, light, etc. is applied to a certain point on the display surface, the position detecting means detects such a point and supplies a corresponding information signal to the display device. The display device alters an image being displayed.
Examples of the position detecting means are a touch panel using a transparent resistive film or a transparent electrode matrix, and an infrared sensor.
Recently, an apparatus using a liquid crystal electro-optical device as the image information display means is commonly used as the above type of information input/output apparatus.
With the above configuration, an operator can perform an input operation while feeling as if he were directly operating the display contents of the display device. If input information is displayed, on a realtime basis, on the same coordinate system of the display device, the operator can input characters or an image while feeling as if he were writing those on a sheet with a writing tool.
However, there have occurred various problems in implementing the conventional configuration using the liquid crystal electro-optical device.
For example, when pressure is exerted on the display surface of the liquid crystal electro-optical device, the orientation of a liquid crystal material incorporated in the liquid crystal electro-optical device may be disordered, disabling a correct display.
Further, magnetism, static electricity, etc. to indicate a position on the display surface may vary display contents, or destroy elements formed on the liquid crystal electro-optical device, to make it incapable of display from that time on. Most of information input schemes are such that an operator moves a pen or a finger while touching the display surface therewith. In those schemes, such information as a document or an image cannot be inputted as a whole.
The above problems could be solved by a configuration in which the liquid crystal electro-optical device is not affected at all by an external force exerted on the display surface.
A projection type liquid crystal electro-optical device (liquid crystal projector) is known as a liquid crystal electro-optical device capable of having such a configuration.
The projection type liquid crystal electro-optical device is compact, light in weight and free of adjustments while being capable of large-screen display with a diagonal dimension of more than 40 inches. Further, it is not affected by the geomagnetism unlike the case of a large-sized CRT. Having such advantages, the projection type liquid crystal electro-optical device is expected to become a display device that will replace a large-screen CRT.
The basic configuration of the projection type liquid crystal display device is such that light is inputted to a transmission or reflection type liquid crystal electro-optical device and resulting transmission or reflection light is expanded by an optical system, to thereby project and display an image on a screen (display surface).
The projection type liquid crystal electro-optical device is classified into the front type in which light is projected onto the display side (front side) of the screen and reflection light is viewed as an image, and the rear type in which light is projected onto the side (rear side) of the screen opposite to the display side and transmission light, i.e., scattered light is viewed as an image.
However, although the projection type liquid crystal electro-optical device is capable of large-screen display, there is no apparatus which causes an information signal indicating a position on the screen (display surface) arbitrarily designated through the display surface to be sent to the display device, and alters its display contents accordingly.
Therefore, although the projection type liquid crystal electro-optical device can display images of a movie or a TV program, it has not been used in a field in which a large-sized screen is required to facilitate operations in connection with CAD or workstation.
An object of the present invention is to provide an information input/output apparatus which allows an operator to input information of a position on the screen of a projection type liquid crystal electro-optical device by designating the position with a pen, a finger, or the like, and which can alter display contents of the liquid crystal electro-optical device accordingly.
Another object of the invention is to provide an information input/output apparatus which can alter display contents of a display device that displays an image on a large-sized screen viewable by a number of persons in accordance with information directly inputted with respect to the display surface.
To attain the above objects, the invention employs the following constitution. That is, according to the invention, an information input/output apparatus comprises:
a display device (an electro-optical device);
a screen on which an image displayed on the display device (electro-optical device) is projected with magnification; and
position detecting means for detecting a position of an arbitrarily designated particular point on the screen.
Further, according to the invention, an information input/output apparatus comprises:
a liquid crystal electro-optical device;
a screen on whose rear surface an image displayed on the liquid crystal electro-optical device is projected with magnification; and
an image pickup device provided on a rear side of the screen, for receiving light entering the screen from its front side to its rear side.
Furthermore, according to the invention, an information input/output apparatus comprises:
a liquid crystal electro-optical device;
a screen on whose rear surface an image displayed on the liquid crystal electro-optical device is projected with magnification; and
an image pickup device provided on a rear side of the screen, for reading an image existing on a front side of the screen.
Still further, according to the invention, an information input/output apparatus comprises:
a liquid crystal electro-optical device;
a screen on whose rear surface an image displayed on the liquid crystal electro-optical device is projected with magnification;
an image pickup device provided on a rear side of the screen, for reading an image existing on a front side of the screen; and
position detecting means provided on the front side of the screen, for detecting a position of an arbitrarily designated particular point on the screen.